Horner syndrome is ptosis, miosis, and anhidrosis due to dysfunction of cervical sympathetic output.
Horner syndrome results when the cervical sympathetic pathway running from the hypothalamus to the eye is disrupted. The causative lesion may be primary (including congenital) or secondary to another disorder. Lesions are usually divided into
Peripheral lesions may be preganglionic or postganglionic in origin.
Symptoms and Signs
Symptoms include ptosis, miosis, anhidrosis, and hyperemia of the affected side. In the congenital form, the iris does not become pigmented and remains blue-gray.
Instilling eyedrops can help confirm and characterize Horner syndrome. First, cocaine (4 to 5%) or apraclonidine (0.5%) drops are put in both eyes. The following results suggest Horner syndrome:
If results suggest Horner syndrome, hydroxyamphetamine (1%) can be put in both eyes 48 h later to locate the lesion, as follows:
Patients with Horner syndrome require MRI or CT of the brain, spinal cord, chest, or neck, depending on clinical suspicion.
The cause, if identified, is treated; there is no treatment for primary Horner syndrome.
Last full review/revision April 2013 by Phillip Low, MD
Content last modified August 2013